1386England and Portugal formally ratify their alliance with the signing of the Treaty of Windsor, making it the oldest diplomatic alliance in the world which is still in force.
1450Timurid monarch 'Abd al-Latif is assassinated.
1662The figure who later became Mr. Punch makes his first recorded appearance in England.
1671Thomas Blood, disguised as a clergyman, attempts to steal England's Crown Jewels from the Tower of London.
1726Five men arrested during a raid on Mother Clap's molly house in London are executed at Tyburn.
1761Exhibition of 1761, the inaugural exhibition of the Society of Artists of Great Britain, opens at Spring Gardens in London.
1864Second Schleswig War: The Danish navy defeats the Austrian and Prussian fleets in the Battle of Heligoland.
1865American Civil War: Nathan Bedford Forrest surrenders his forces at Gainesville, Alabama.
1865American Civil War: President Andrew Johnson issues a proclamation ending belligerent rights of the rebels and enjoining foreign nations to intern or expel Confederate ships.
1873Der Krach: The Vienna stock exchange crash begins the Panic of 1873 and heralds the Long Depression.
1877Mihail Kogălniceanu reads, in the Chamber of Deputies, the Declaration of Independence of Romania. The date will become recognised as the Independence Day of Romania.
1901Australia opens its first national parliament in Melbourne.
1915World War I: Second Battle of Artois between German and French forces.
1918World War I: Germany repels Britain's second attempt to blockade the port of Ostend, Belgium.
1920Polish–Soviet War: The Polish army under General Edward Rydz-Śmigły celebrates its capture of Kiev with a victory parade on Khreshchatyk.
1926Admiral Richard E. Byrd and Floyd Bennett claim to have flown over the North Pole (later discovery of Byrd's diary appears to cast some doubt on the claim).
1927The Old Parliament House, Canberra, Australia, officially opens.
1936Italy formally annexes Ethiopia after taking the capital Addis Ababa on May 5.
1941World War II: The German submarine U-110 is captured by the Royal Navy. On board is the latest Enigma machine which Allied cryptographers later use to break coded German messages.
1942The Holocaust in Ukraine: The SS executes 588 Jewish residents of the Podolian town of Zinkiv (Khmelnytska oblast). The Zoludek Ghetto (in Belarus) is destroyed and all its inhabitants executed or deported.
1945World War II: The Channel Islands are liberated from Nazi occupation.
1946King Victor Emmanuel III of Italy abdicates and is succeeded by Umberto II.
1948Czechoslovakia's Ninth-of-May Constitution comes into effect.
1950Robert Schuman presents the "Schuman Declaration", considered by some to be the beginning of the creation of what is now the European Union.
1960The Food and Drug Administration announces it will approve birth control as an additional indication for Searle's Enovid, making Enovid the world's first approved oral contraceptive pill.
1969Carlos Lamarca leads the first urban guerrilla action against the military dictatorship of Brazil in São Paulo, by robbing two banks.
1974Watergate scandal: The United States House Committee on the Judiciary opens formal and public impeachment hearings against President Richard Nixon.
1979Iranian Jewish businessman Habib Elghanian is executed by firing squad in Tehran, prompting the mass exodus of the once 100,000-strong Jewish community of Iran.
1980In Florida, United States, Liberian freighter collides with the Sunshine Skyway Bridge over Tampa Bay, making a section of the southbound span collapse. Thirty-five people in six cars and a Greyhound bus fall into the water and die.
1980In Norco, California, United States, five masked gunmen hold up a Security Pacific bank, leading to a violent shoot-out and one of the largest pursuits in California history. Two of the gunmen and one police officer are killed and thirty-three police and civilian vehicles are destroyed in the chase.
1987LOT Flight 5055 Tadeusz Kościuszko crashes after takeoff in Warsaw, Poland, killing all 183 people on board.
1992Westray Mine disaster kills 26 workers in Nova Scotia, Canada.
1999Mother's Day bus crash kills 22 passengers and injures another 22, including the driver in New Orleans, Louisiana, United States.
2001In Ghana, 129 football fans die in what became known as the Accra Sports Stadium disaster. The deaths are caused by a stampede (caused by the firing of tear gas by police personnel at the stadium) that followed a controversial decision by the referee.
2002The 38-day stand-off in the Church of the Nativity in Bethlehem comes to an end when the Palestinians inside agree to have 13 suspected terrorists among them deported to several different countries.
2018Barisan Nasional, the coalition that had governed Malaysia since the country's independence in 1957, suffer a historic defeat in the 2018 Malaysian general election.
2020The COVID-19 recession causes the U.S. unemployment rate to hit 14.9 percent, its worst rate since the Great Depression.
2022Russo-Ukrainian war: United States President Joe Biden signs the 2022 Lend-Lease Act into law, a rebooted World War II-era policy attempting to expedite American equipment to Ukraine and other Eastern European countries.
2023The May 9 riots following the arrest of Imran Khan in Pakistan.
Victory Day observances, celebration of the Soviet Union victory over Nazi Germany (Soviet Union, Azerbaijan, Belarus, Bosnia and Herzegovina, Georgia, Israel, Kazakhstan, Kyrgyzstan, Moldova, Russia, Serbia, Tajikistan, Turkmenistan, Uzbekistan)